Hydraulic shear



R. P. ANDERSON ET AI. 2,931,182

HYDRAULIC sHEAR 5 Sheets-Sheet 1 ....q, I-l IVI. .II .IlIlIvlllHIIIIPIIIII K April 5, 1960 Filed Aprille', 1957 INVENTORS Pay 05x04 ByRap/f EAA/@Epson III III

I I I I I I l l I I I I I I I I l I I I IM @S April 5, 1960 R. P.ANDERSON r-:TAL 2,931,182

HYDRAULIC SHEAR n Filed April 15, 1957 5 Sheets-Sheet 2 .Il l MN April5, 1960 R. P. ANDERSON E-rAL 2,931,182

HYDRAULIC SHEAR Filed April 16, 1957 5 Sheets-Sheet. 3

INVENToRs Por f-T DEH/v BY RALPH RANQERSON April 5, 1960v R. P. ANDERsoNETAL 2,931,182

HYDRAULIC sHEAR Filed April 16, 1957 5 Sheets-Sheet 4 @XR m f @i LJ sw/R d [im Q E? @A [t Q gg nx.) y@

April 5., 1960 R. P. ANDERSON Erm. 2,931,182

HYDRAULIC SHEAR 5 Sheets-Sheet 5 Filed April 16, 1957 INVENTUM` Psy EOEHN By PAL/H EAA/msm t. l m, '1.'

Armas-Ys United States HYDRAULIC SEMAR Application April 16, 1957,Serial No. 653,238

4 Claims. (Cl. 60-97) The present invention relates to devices having amovable member actuated by a plurality of reciprocating type hydraulicmotors and wherein it is necessary or desirable to have the movablemember travel or move in a predetermined manner with respect to astationary member or some predetermined reference plane.

One of the principal objects of the invention is the provision of anovel and improved device for cutting or otherwise fabricating sheetmaterial or the like, for example, a shear, platen press, press brake,etc., having a movable member of substantial size in at least onedimension actuated by a plurality of reciprocating type double actinghydraulic motors connected to the movable member at relatively widelyspaced points which machine will be relatively light in weight, simplein design and rigid in construction, reliable in operation and whichcomprises means for supplying pressure uid to the respective motors insuch a manner that the movable member moves, preferably in bothdirections, in a relatively exact or precise predetermined attitude ormanner, for example, parallel with or inclined at a predetermined angleto the stationary platen, blade, etc.

A more specific object of the invention is the provision of a novel andimproved metal working shear or press brake having an elongated movableblade actuated by a pair of reciprocating type double acting uidpressure operated motors connected to the movable blade adjacent toopposite ends thereof in combination with means for supplying pressurefluid to the motors and including a Wheatstone bridge responsive todeviation of the blade from a predetermined attitude relative to thestationary blade or die for controlling the relative ow of pressure uidto the motors whereby the blade is automatically restored to thepredetermined attitude or a predetermined attitude is maintained.

Another of the principal objects of the invention is the provision of anovel and improved means for controlling the supply or flow of fluidpressure to a plurality of reciprocating type hydraulic motorspreferably of the double acting type such that the motors are operatedin precise predetermined relation to one another.

The invention resides in certain constructions and combinations andarrangements of parts and further objects and advantages will beapparent to those skilled in the art to which it relates from thefollowing description of the preferred embodiment described withreference to the accompanying drawings forming a part of thisspecification in which similar reference characters designatecorresponding parts and in which Fig. 1 is a front elevational View of asheet metal or plate shear embodying the present invention;

f Fig. 2 is a rear view of the shear shown in Fig. 1;

. Fig. 3 is a sectional view of the shear approximately on the line 3 3of Fig. l;

. Fig. 4 is a diagrammatic view showing the hydraulic system and themechanical part of the leveling control; and

arent Fig. 5 is a wiring diagram showing the electrical control for theshear.

The present invention is considered especially applicable to sheet metalor plate shears and bending brakes and is herein shown as embodied insuch a shear. The invention however, is applicable to various types ofshears, presses and other machines utilizing multiple pressure fluidoperated reciprocating type motors and the present showing is intendedto be merely illustrative of the invention and not to be restrictive inany manner.

Referring to the drawings, the shear shown includes a frame A comprisingstress-resisting, plate-like end members or side housings 10, 11 havingaligned openings 12, 13 respectively, in their front edges; a crown 14connecting the upper ends of the side housings 10, 11; and a table 15supported upon and fixedly secured to the top of forwardly projectingparts of the side housings 10, 11 and a heavy plate or stationary blade16 extending between and fixedly secured to the side housings 10, 11.

A movable ram or upper blade, designated generally by the referencecharacter B, extends substantially from one side housing to the otherand is of built-up construction. As shown, the movable ram or blade Bcomprises a longitudinally extending front plate 20 welded to the frontends of rearwardly extending members 21, 22, the rear ends of which arerotatably connected to short, shaftlike members 23, 24 rotatablysupported in suitable apertures in the side housings 10, 11,respectively, for rotation about an axis eccentric to the axis aboutwhich the members 21, 22 are connected thereto. The axis about which theram or blade B is pivoted is preferably slightly above the plane of thework supporting surface of the table 15.

In addition to the front plate 20 and the members or plates 21, 22 themovable ram or upper blade B comprises a lbotto-n1 plate 25 having anupwardly extending rear flange 26. The ends of the front edge of thebottom plate 25 abut against and are welded to the rear side of theplate 20 adjacent to the lower edge thereof While the ends thereof arewelded to the members 21, 22. The intermediate part of the front edge ofthe bottom plate 25 is welded to a plate 27 spaced slightly to the rearof the plate 20. The blade assembly is further reinforced by web members29, Sil, 31, 32, 33 welded to the plates 20, 27 and the bottom plate 25and by triangular plates weldedto the rear side of the bottom plate 25and the members 21, 22.

The shearing operation is performed by a stationary relatively long,narrow, thin shearing knife 40 located in a cutout portion at the upperrear edge of the stationary blade or member 16 and a movable shearingknife 41 of similar shape connected to the lower front edge of the plate20 of the movable ram or b-lade B. 'I'he plate 20 of the blade B isinclined at a slight angle to the vertical to provide clearancetherebetween and the stationary knife 40 when the ram or blade B isoscillated, and the lower front edge of the plate 20 is inclinedlengthwise so that the knives 40, 41 will effect a true shearing action.

In the shear press shown, the axis of rotation of the blade B isparallel to the cutting edge of the stationary shearing knife 40, whilethe cutting edge of the movable shearing knife 41 is inclined lengthwiserelative to the cutting edge of the stationary shearing knife 40 and tothe axis of rotation of the blade B. Preferably the stationary knife 40has a straight or linear cutting edge. With such an arrangement, toefect a uniform clearance between the cutting edges of the shearingknives throughout their ,longitudinal length during shearing movement ofthe blade B, the movable shearing knife 41 must have its cutting edgepositioned on the surface of a cylinder the center of which iscoincidentY with the axisof rota tion of the blade B, i.e. its cuttingedge must be curved l outwardly a slight amount so as to form a segmentof a helix having a very long pitch and an axis coincident withtheaxiswof rotation of blade B. The movable blade B and the knife 41carried thereby are adjusted toward and from the stationary blade C andknife 4t! carried thereby to adjust the clearance between the` knives byrotation or adjustment of the eccentric shaft-like members 23, 24.

The front end of the ram or movable blade B is supported and the entireblade assembly is adapted to be oscillated about the shafts 23, 24 byreciprocating type double acting fluid pressure motors designatedgenerally by reference characters E and F. The cylinders 47, 48 of themotors E and F, respectively, are connected to the crown 14 of the pressand the piston rods 59, 51 of the motors are connected by links 52, 53to pivot pins 54, 55 iixed to the blade B adjacent to opposite endsthereof. Pressure fluid preferably oil, for operating the hydraulicmotors is adapted to be supplied 'oy a constant volume unidirectionalpump G adapted to be driven Iby an electric motor 56. The pump and motoras well as a number of the other parts of the hydraulic system aresupported upon the top of an elongated rectangular oil tank or sump Sextending between and connected to opposite end housings 1i), 11 of theframe A.

The ow of uid pressure, preferably oil, to and from the cylinders 47, 48is controlled by a pair of solenoid operated three-way valves 6), 61cross connected to the cylinders, that is, each valve is connected toone end on one cylinder and to the opposite end of the other cylinder.In the embodiment shown the valve 60 is connected to the upper end ofcylinder 47 and the lower end of cylinder 48 and the -valve 61 isconnected to the upper end of cylinder 48 and the lower end of cylinder47. Both valves 66, 61 are normally spring balanced to their oficpositions wherein the supply conduit 62 therebetween and the pump areconnected to the oil reservoir or sump S.

Referring to the wiring diagram and assuming that the motor 56 is inoperation and the movable blade B is in its raised position, the bladeis caused to move in a downwardly direction by the operator depressing apedal 65 forming a part of a control box 66 connected to the free end ofa flexible electrical cord so that it can be moved to a convenientlocation. The depressing of the pedal 65 closes a normally open switch67 establishing an electrical circuit from the alternating currentelectric power supply line 68 through the normally Aclosed contacts of amechanical overtravel limit switch 69, wire 76, normally closed contacts71 of a relay 72, wire 73, now closed contacts of pedal switch 67, wire74, normally closed down limit switch '75, wire 76, normallyclosed'interlock contacts 77 of blade up relay 78, wire 79, operatingsolenoid 80 of blade down relay 81 to power supply line 82. Energizationof the operating solenoid 80 of relay 81 closes the normally opencontacts `85 thereof which establishes a parallel or holding circuitabout the pedal switch 67, assuming that the manually operable on-oiswitch 86 is closed. The establishment of the holding circuit about thepedal switch 67 permits the operator to release the pedal switch. lf amanually operable switch 86 is open, the holding circuit will not beestablished for the pedal switch 67 and the blade down relay 81 willremain energized only so long as the operator holds the pedal switch 67closed.

f Energization of the operating solenoid 80 of the blade down relay 81,as previously described, opens the normally closed interlock contacts 90preventing energize.- tion of the blade up relay 78 while the blade downrelay 81 is energized. Simultaneously with the closing of the holdingcontacts 85 and the opening of interlockcontacts 90 of relay 81,normally open contacts 91 thereof close establishing a circuit from thepower supply line 68 through the now closed contacts 91 of blade downrelay 81, wire 92 and operating solenoids 93, 94 of solenoid valves 60,61 respectively. Energization of the solenoids 93, 94 shift the valves60, 61 respectively to the positions in which the supply line 62 fromthe pump G is connected, through the valve 6i) and the conduit 95 to theupper end of the cylinder 47 and through the valve 61 and the conduit 96to the upper end of the cylinder 18. The opposite or lower end of thecylinders 47, 48 are simultaneously connected through conduit 97, acounterbalancing valve 98, conduit 99, the valve 61 and conduit 16o tothe reservoir or sump S and the lower end of the cylinder 48 isconnected in a similar manner by a counterbalancing valve 101 and avalve 60 to the reservoir or sump S. The counterbalancing valves 98, 101open when the pressure in the lower ends of the cylinders 47, 48 reachesa predetermined pressure and are provided for the purpose of makingcertain that the movable ram or blade does not drop under its own weightwhen the valves 69, 61 are in neutral position.

With the respective parts in the operative position referred to theblade continues to move down until the down limit switch '.71 fixed tothe frame A and actuated by travel of the movable blade B is opened thusbreaking the circuit to the blade down relay 81. When the circuit forthis relay is broken its normally closed interlock contacts 913 recloseestablishing a circuit from the wire 73 through the now closed interlockcontacts 90 of the blade down relay 81, wire 165, normally closedcontacts of up limit switch 166, wire 107 and operating solenoid 168 ofblade up relay '78 to power supply line 82. The energization of blade uprelay 78 opens its normally closed interlock contacts 7"? thuspreventing reenergization of blade down relay 81 and closes its nor.-mally open contacts 11).

The closing of the normally open contacts 110 of blade up relay '78establishes a circuit from the power supply line 68 through the nowclosed contacts 110 of blade up relay 78, wire 111 and operatingsolenoids 112, 113 of solenoid operated valves 60, 61 respectively topower supply line 82. The operating solenoids 112, 113, like thesolenoids 93, 94, are in parallel circuit, and their energizationactuates the respective valves 60, 61 with which they are associated toconnect the lower ends of the cylinders 47, 48 to the pressure fluidsupply line 6Z`and the upper ends of the cylinders to the reservoir orsump. The counterbalancing valves 98, 101 previously referred to arebypassed by checkvalves 114, respectively. The application of pressurefluid to the lower ends of the cylinders 47, 4S causes the blade to movein an upwardlyy direction which movement of the blade continues untilthe circuit for the blade up relay 78 is broken by the opening of thenormally closed contacts of the up limit switch 196 carried by the frameA of the press and actuated by movement of the blade B in an upwardlydirection. The cycle of operation can `be repeated by the operator againdepressing the pedal 65 to reclose the pedal controlled normally openswitch 67. A manual switch 115 connected between the wires 68 and 73provides means for returning the blade to its up position in the eventthe shear is operated with the switch 86 open.

lt will be apparent that as a shearing operation is performed, the loador resistance to movement of the shear blade B will not be uniformlydistributed'throughout the length of the blade or between the twohydraulic motorsE and F except during the performance of the cuttingoperation at the exact middle of the machine. 1f a relatively wide sheetis to be sheared, the cutting operation will begin at one end of theknives and progress toward the other end with the result that a greaterresistance will be encountered by that end of theV movable I bladeadjacent to the hydraulic motor F at the beginning of the shearingoperation. This resistance encountered by the motor F will graduallydecrease or be transferred to the motor E at the opposite side of theshear as the shearing operation progresses. In the operation of shearsof the` character shown, it is desirable in most instances to have themovable blade B remain at a constant angle with respect to the xed bladethroughout the shearing operation and the present press incorporatesmeans for controlling the ow of pressure fluid to the respective motorsin such a manner that they move at a uniform.

speed regardless of the resistance encountered.

In the embodiment of the invention shown, this mechanism, hereinreferred to as the blade attitude or leveling control, includes a bladeattitude sensing mechanism comprising an electric bridge designatedgenerally as I and located in the housing 118 which bridge produces asignal when the blade is out of attitude or level and an amplifyingcircuit for determining the polarity and magnitude of the signal andchanging the flow of pressure iluid to the respective motors inaccordance to the signal, to restore the blade to its predeterminedangular position relative to the xed blade.

The attitude sensing mechanism shown comprises an H-shaped armature 120made of magnetic material and having an electric coil surrounding eachof the respective arms of the armature. The coils are designated 121,122, 123, 124 and are connected to the alternating current power supplylines 68, 82 in such a manner that they form an impedance bridge of thereactor type. 'I'he coils 121-124 are llixed to the frame of the shear,in the present instance to the left-hand side housing 10, and thearmature 120 is slidably supported by the housing for movement in agenerally vertical direction parallel with the length of the respectivearms or cores thereof. The armature120 is biased in an upwardlydirection by tension spring 125 connected thereto and to a pin 126connected to the side housing of the shear and is adapted tov be movedin a downwardly direction by a relatively non-elastic, iiexible steelband 127 connected thereto and extending in a downwardly direction fromthe armature, that is, in a direction opposite to the tension spring125. From the armature 120 flexible steel band 127 passes about a sheave130 fixed to the front of the movable blade B adjacent to the left-handend of the blade as viewed in Fig. 1. From the sheave 130 the flexibleband extends generally horizontally across the front of the blade B andpasses over a sheave 1311 pivotaly connected to a member 132 on theright-hand end of the blade B which extends to the outside of therighthand side plate 11 through an elongated slot 133 in the side plate.From the sheave 131 the flexible steel band 127 extends downwardly in agenerally vertical direction and has its end secured to a disk-likemember 134 rotatably connected to the side housing 11 and provided witha hand grasp and means for ixedly securing it in any adjusted position.By adjusting the member 134, the armature 120 can be adjusted relativeto the coils 121- 124 to balance the bridge circuit, etc.

From the foregoing it will be apparent that with the electric bridge inbalance at the beginning of the shearing operation any variation orchange in the attitude or level of the blade B with reference to the xedknife 40 Will cause the bridge to become unbalanced and a signal toappear across its terminals. 'I'he magnitude and polarity of the signalwill be a function of the blade attitude and while this signal could beemployed to effect a continuous control upon the ow of pressure fluid tothe respective motors E, F at opposite ends of the blade B, in theembodiment of the invention shown the signal is applied to an amplifyingcircuit comprising a plurality of thyratron tubes which, in turn,interrupt the flow of pressure fluid to one or the other of the motorsE, F, depending upon which end ofthe blade is leading the other.

A complete circuit is shown in the wiring diagram but will not be hereindescribed in detail. Suce it to say that it includes means for adjustingthe amount of unbalance required in the bridge circuit to fire therespective thyratron tubes 137, 138, the grid circuits of which areconnected to the output or control terminals 140, 141 of the bridge. Theplate circuits of the tubes 137, 138 are connected to operatingsolenoids 142, 143 of relays 144, 145 having normally open contacts 146,147 in series circuit with operating solenoids 150, 1511 of normallyopen two-way valves 152, 153 in the pressure uid supply lines to therespective valves 60, 61 which control the actuation of the iluidpressure motors E, F respectively.

When a positive bias or signal appears on the grid circuit of the tube137, a negative bias appears on the grid circuit of the tube 138 andvice versa; Assuming that the grid bias of tube 137 is positive and ofsuicient amplitude to lire the tube, relay 144 is operated to close itsnormally open contacts 146 and energize the solenoid 150 of valve 152thereby actuating the valve to discontinue the ilow of pressure fluid tothe valve 60 and the left-hand motor E. The signal regains control ofthe tube 137 after each half cycle and as long as a positive bias inexcess of the predetermined'amount remains on the grid circuit of tube137, the llow of pressure lluid to motor E will be discontinued. As soonas the other or right-hand end of the blade catches up with theleft-hand end the positive bias disappears from the grid of the tube 137and pressure fluid is again applied to both motors and the bladecontinues its movement until it reaches the end of the stroke. If eitherend ofthe blade leads the other end at any time the blade will bereturned to the desired attitude'automatically. In the embodiment shown,the relay 72 previously referred to is in the nature of a safety deviceand is connected to the bridge circuit terminals 140, 141 in such amanner and is of such a character that in the event the out-of-attitudecondition of the blade B exceeds a predetermined amount in excess of theamount required to tire the tubes 137, 138, the normally closed contacts71 of the relay will be opened to stop the shear. Y

The safety feature imparted by the relay 72 can be omitted altogether ifdesired or the relay can be replaced or supplemented with some suitablealternative control, for example, the normally closed contacts 71 of therelay 72 could be replaced by a normally closed limit switch connectedto the side housing 10 of the press in such a manner that its contactswould be opened by movement of the armature 120 Yin either direction inexcess of a predetermined amount. 'Ihe present control is capable ofextreme sensitivity to variations in blade attitude regardless of thedirection in which the blade is movmg.

While in the embodiment shown an out-of-attitude condition is correctedby discontinuing the llow of pressure iuid to one or the other of thehydraulic motors, the invention contemplates as an alternativeconstruction merely reducing the ow of pressure iluid to the leadingmotor as distinguished from discontinuing it entirely. In the embodimentshown, this is readily accomplished by providing the valves 152, 153with high resistance bypasses.

The invention also contemplates as an alternative construction the useof reversible variable volume pumps 'connected directly to the hydraulicmotors in a manner similar to that in which the valves 60, 61 areconnected thereto and the controlling of the volume and direction ofoperation of the respective pumps by solenoids similar to the solenoids93, 94, 112, 113, 150, 151. The solenoids 93, 94, 112, 113 would, forexample, control the direction of operation vof the respective pumps andthe solenoids 150, 151 would be used to either return the respectivepumps to zero volume or to reduce the output volume, as desired.

From the lforegoing it will be apparent that the objects heretofore setforth and others have been accomplished and that a novel and improveddevice, such as a shear,

has been provided having a member movable by a plurality of pressure uidoperated motors connected thereto at relatively widely spaced points andmeans for supplying pressure iiuid to the motors including an electricbridge responsive to Variations of the member from a predeterminedattitude relative to a reference line for controlling the relative ow ofpressure iluid to the motors to maintain a predetermined attitude. Whilethe preferred embodiment and alternative constructions thereof have beendescribed and referred to in considerable detail and while the bridgeshown is of the reactor type, the invention is not limited to theconstructions or to the type of bridge shown and it `is the intention tohereby cover all adaptations, modications and uses thereof which comewithin the scope of the appended claims. The term impedance as usedherein includes either resistors and/ or reactors.

Having thus Vdescribed our invention wc cla-im:

l. ln a device of the character described a supporting means, a member,a plurality of pressure fluid operated motors connected to saidsupporting means and to said member at spaced points `for producingmovement of said member relative to said support, means for supplyingpressure iluid to said motors, an electric bridge including two parallelcircuits each comprising a plurality of electric impedance means, meansresponsive to variations of said member from a predetermined attituderelative to said supporting means for varying the impedance of one ofsaid impedance means, and means connected across said parailel circuitsintermediate two of said impedance means in each circuit for controllingthe supply of pressure iluid to said motors to maintain a predeterminedattitude.

2. In a device of the character described a supporting means, a mem-ber,a plurality of pressure fluid operated motors connected to saidsupporting means and to said member at spaced points for producingmovement of said member relative to said support, a source of fluidpressure, means including electric solenoid means for controlling theiiow of pressure fluid to and from said motors, an electric circuit forcontrolling the energization and deenergization of said solenoid means,said circuit including an electric impedance bridge means comprising twoparallel circuits each including a plurality of electric reactor means,armature means forming a part of said bridge means, means operativelyconnected to said supporting means and to said member for varying therelative position of said armature means in response to variations ofsaid member from a predetermined attitude relative to said supportingmeans, and means connected across said parallel circuits intermediatetwo or said impedance means in each circuit for controlling the flow ofpressure iluid to said motors to maintain said predetermined attitude.

3. In a device of the character described, a supporting means, -amember, a plurality of pressure tluid operating motors connected to saidsupporting means and to said member at spaced points for moving saidmember relative to said supporting means, a source of pressure fluid,electric solenoid operated valve means for selectively connecting anddisconnecting said source of pressure fluid 6 to and from said motor, anelectric circuit including an electric bridge .means having two parallelcircuits each comprising a plurality of electric impedance means, mov--able control means forming a part of said bridge means for varying theimpedance of Vone of said impedance means, means operatively connectedto said supporting means and to said member for moving said movablecontrol means of said electric bridge means in responseA to variationsof said member from a predetermined attitude relative to said supportingmeans to'cause a signal or voltage to a ear across oints in said arallelcircuits intermediate two of said impedances in each of said circuitsthe magnitude and polarity of which is a function of the variation ofsaid member from said predetermined attitude, an amplifying circuitcomprising thyratron tubes having their grid or control elementsconnected to said points in said parallel circuits of said bridge meansintermediate two of said impedance means of each circuit such that saidtubes are responsive to voltages of different polarity, and means foroperatively connecting the plate circuits of said thyratron tubes toSaid solenoid operated valve means for energizing and de-energizing saidsolenoid operated valve means to maintain said member within apredetermined attitude range relative to said lsupporting means.

4. In a device of the character described, a supporting means, a member,a plurality of pressure fluid operating motors connected to saidsupporting means and to said member at spaced points for moving saidmember relative to said supporting means, a source of pressure fluid,electric solenoid operated valve means for selectively connecting andVdisconnecting said source of pressure iiuid to and `from said motor, anelectriccircuit including an electric bridge means having two paralelcircuits each comprising a plurality of electric impedance means, a pairof output terminals connected to said parallel circuits intermediate twoof said impedances, movable control means forming a part of said bridgemeans for varying the impedance of one of said` impedance means, meansoperatively connected to said supporting means and to said member formoving said movable control means in said electric bridge means inresponse to variations of said member from a predetermined attituderelative to said supporting means to cause a voltage to appear acrosspoints in said parallel circuits intermediate two of said impedances ineach of said circuits of said bridge means the magnitude and polarity ofwhich is a function of the variation of said member from saidpredetermined attitude, an electric switching means comprising a controlcircuit and a controlled circuit means connecting said control circuitto said points in said parallel circuits of said bridge meansintermediate two of said impedance means, and means operativelyconnecting said controlled circuit of said switching means to saidsolenoid operated valve means for energizing and de-energizing saidsolenoid operated valve means to maintain said member within apredetermined attitude range relative to said supporting means.

References Cited in the file of this patent UNITED STATES PATENTS2,378,497 Phillips June 19, 1945 2,558,071 Castle et al. June 26, 19912,565,639 Waldie Aug. 28, 1951

